1. Field of the Invention
The present invention relates to a method and device for the extraction of hair grafts from the donor area of a patient for subsequent transplantation to a recipient area. More specifically, the present invention relates to a method and device for the extraction of follicular hair units that decreases the follicular transection rate and improves the yield of transplantable follicular units.
2. Description of Related Art
The basic process of hair transplantation is to remove hair from the side and back fringe areas (donor areas) of the patient's head, and move it to the bald area (recipient area). Historically, 4 mm diameter plugs were utilized as the donor plug; this was followed by mini-grafts (smaller plugs), and finally by follicular units grafts (FUG's). FUG's are naturally occurring aggregates of 3-5 closely spaced hair follicles. The FUG's are distributed randomly over the surface of the scalp.
In the foregoing processes, a linear portion of the scalp is removed from the donor area by dissection with a scalpel. Some follicles are invariably transected during this process, damaging the follicles. In addition to some follicular damage, the removal of this donor strip will always result in a scar. In addition to the scar, there is usually a degree of moderate pain for several days and a sensation of tightness for 6-8 weeks following the procedure. Multiple procedures will result in multiple scars and thinning of the hair above and below the scar. If the pliability or laxity of the scalp is miscalculated, and a strip that is too wide is removed, this procedure has the potential to create a wide, unsightly scar because of the tension required to close the wound. Sometimes the resulting scar can be difficult to hide or disguise, causing a significant cosmetic deformity.
FUG's are dissected from a donor strip by several technicians using operating microscopes. Often the best technicians can produce approximately 250 to 300 grafts per hour, and an average technician produces closer to 200 grafts per hour. The FUG's are sorted into groups based upon the number of hairs contained in the FUG. The best technicians will have a transection rate of from about 2% to 5%.
Recently, Dr. William Rassman and Dr. Robert Bernstein disclosed a technique, called follicular unit extraction (FUE), whereby follicular units were extracted from the donor area without the need to create a linear incision with a scalpel. This was accomplished by using a sharp 1 mm diameter punch to make an incision into the epidermis and dermis, and then removing the follicular unit from the surrounding skin with forceps. Their findings suggested that some follicles were easily removed; others had a significant tendency to shear in the process. By their research, a good candidate was defined as one who experienced less than 20% shearing, and only about 25% of the patients tested were considered good candidates by their shearing test. This test is called the FOX (FOllicular eXtraction) test.
The foregoing procedure is technically difficult, as the penetration depth and penetration angle is difficult to control. If the sharp punch penetrates too deeply or at the incorrect angle there is a good chance of transecting the follicular unit. This method has not been widely adopted due to the problems of transection, difficulty removing the grafts, the time required to produce the grafts, and the low percentage of potential candidates
Dr. John Cole, an expert in FUE, devised a device that limits the depth of the sharp punch to just below the attachment of the arrector pili muscle (presumably responsible for tethering the FUG to the deeper tissues and causing shearing during extraction), and increases the number of viable grafts produced. He has called his procedure the FIT, or Follicular Isolation Technique. He reports on his website that he has produced and transplanted up to 1200 grafts in one day. It is not believed that the time required to accomplish this has been more accurately reported.
The dissection of grafts from the scalps of African Americans and those with a high percentage of gray or white hairs is particularly problematic. The African American's follicles typically have a high degree of curl or curve, making the dissection difficult and prone to high transection rates. The follicles of white or gray hair are all but invisible, even under the microscope, making them prone to a high rate of transection as well.
There remains a need for a follicular extraction method and related device that reduces the amount of follicular transection and increases the follicular extraction rate.